Abstract [en]

This study analyzes the amount of material deposited in Swedish municipal solid waste landfills, how much is extractable and recyclable, and what the resource and climate implications are if landfill mining coupled with resource recovery were to be implemented in Sweden. The analysis is based on two scenarios with different conventional separation technologies, one scenario using a mobile separation plant and the other using a more advanced stationary separation plant. Further, the approach uses Monte Carlo simulation to address the uncertainties attached to each of the different processes in the scenarios. Results show that Swedens several thousand municipal landfills contain more than 350 million tonnes (t) of material. If landfill mining combined with resource recovery is implemented using a contemporary stationary separation plant, it would be possible to extract about 7 million t of ferrous metals and 2 million t of nonferrous metals, enough to meet the demand of Swedish industry for ferrous and nonferrous metals for three and eight years, respectively. This study further shows that landfill mining could potentially lead to the equivalent of a one-time reduction of about 50 million t of greenhouse gas emissions (carbon-dioxide equivalents), corresponding to 75% of Swedens annual emissions.

Abstract [en]

Landfill mining is a relatively unproven, still uncertain concept for extracting resources from landfills. Previous studies in the field have mainly focused on solving local environmental problems related to leaching and other landfill management issues, or characterizing the material composition of various landfills. Few, however, have used a systematic approach when evaluating the environmental and economic potential of landfill mining, and fewer still have quantified this potential. Furthermore, discussions regarding the technical, legal, and organizational conditions of landfill mining are largely lacking. This lack of knowledge and experience creates uncertainties that make most landfill mining initiatives high-risk investments and consequently hinders the development of knowledge in the field. The purpose of this thesis is therefore to present the development and application of a systems analysis approach for evaluating the economic and environmental potential of landfill mining designed to handle the uncertainties surrounding this concept.

The approach aims to incorporate all relevant processes related to landfill mining, and to combine LCA methodology with Monte Carlo simulation to incorporate the inherent uncertainties into the result. The approach is based on one or more scenarios, the results of which can be compared with each other, as well as with a reference scenario. The scenarios are constructed using five different aspects that have been identified in previous studies as being relevant for the environmental and economic potential: landfill characteristics, organizational setup, policies and legislation, market conditions, and technology. These scenarios can be set up on a variety of levels, from identifying the impact of strategic policies regarding landfill mining to evaluating small landfill mining projects. The environmental analysis uses LCA and produces results on a global and regional scope, while the economic analysis is done from a project owner’s perspective using direct revenues and costs. Results from the approach can be used not only to see the net result for each scenario, but also to recognize which processes contribute the most to the result, and how important these are relative to other processes.

Results from the environmental potential show the resource potential and climate implications of mining all, or parts of, the Swedish municipal solid waste landfills. The metal content in these landfills corresponds to about three years of ferrous and up to eight years of non-ferrous scrap usage in Sweden. Additionally, the amount of combustible material is enough to cover the Swedish demand for more than five years. If all the landfills in the study were to be remediated and mined of resources, over 50 million metric tons of CO2-equivalent emissions can be avoided, comparable to Swedish annual emissions. The positive result can mainly be attributed to the avoided emissions, created by the material and energy recycling processes.

The economic potential has been analyzed from a landfill owner’s perspective by including direct costs and revenues in the evaluation. The thesis shows that by integrating material recovery into an already planned remediation project, the economic result can improve under certain circumstances. Two of the most important factors, in addition to the material composition of the landfill, were found to be the landfill tax and ownership of, and access to, a combined heat and power plant.

In summary, the thesis shows that there are many potential benefits from recovering resources from landfills, although they are dependent on a variety of factors. Three types of key factors contributing to the environmental and economic potential of landfill mining have been found: site-specific factors, project factors, and external factors. By using the systems analysis approach presented in this thesis, the absolute and relative impact of these factors, regarding both environmental and economic impact for a specific landfill mining project, can be identified.